![]() ![]() with the back-gate terminal tied or connected to the source terminal S) is depicted in prior art FIGS. ![]() ![]() ![]() the voltage difference between the gate terminal and the source terminal (V.sub.GS). Thus, the output current of the transistor M is controlled by the voltage applied to the gate terminal G, e.g. In prior art mixers, the back-gate terminal B is connected to a fixed voltage source such as a power supply or connected to the source terminal S. Transistor M also includes a back-gate terminal (B) 30 which accesses the well region 14 through the major surface 13. The transistor M is used by applying appropriate voltages to its terminals, including a source terminal (S) 24 that accesses the source region 16, a drain terminal (D) 28 for accessing the drain region 18, and the gate terminal (G) 26 for controlling the flow of carriers through the channel region 20. An oxide layer 22 is formed over the channel region, upon which a gate terminal 26 is created for controlling the flow of carriers (in this case p-type carriers) in the channel 20. The source and drain regions are spaced apart and a channel region 20 is induced therebetween when the transistor M is appropriately biased in a manner well-known to those having ordinary skill in the art. Transistor M includes an N-well region 14 in which p+ doped source and drain regions 16, 18 are formed. The depicted MOS transistor 10 (designated as M) is a P channel device that is formed on a P-doped semiconductor substrate 12 having an upper major surface 13. Such a device is depicted in cross-section in FIG. Heretofore known downconverters or mixer circuits employ Metal Oxide Semiconductor (MOS) Field Effect transistors which are operated as three-terminal devices. The resulting output signal or IF signal is frequency shifted or heterodyned by the frequency of the LO signal. Such circuits multiply or mix a received RF signal (provided to the mixer circuit by an antenna, for example) with a local oscillator (LO) signal. Mixer circuits for downconverting received RF signals to a lower center frequency or intermediate frequency (IF) are well known. More particularly, the present invention pertains to a multiple terminal circuit for use as an RF mixer for shifting the center frequencies of input signals. The present invention relates to a circuit element having multiple terminals for multiplying multiple input signals to produce an output signal. Likewise, the positive phase LO signal is applied to two of the transistors and the negative phase LO signal is applied to the other two transistors. In the double balanced circuit, four MOS transistors are used the positive phase RF signal is applied to the gate terminals of two of the transistors and the negative phase RF signal is applied to the gate terminals of the other two transistors. In the single balanced circuit, two MOS transistors are used the RF signal is applied to the gate terminals with the positive phase LO component applied to one back-gate terminal and the negative phase local oscillator (LO) component applied to the other back-gate terminal for producing a positive phase and a negative phase IF signal. A single balanced and a double balanced mixer circuit are also disclosed. A DC voltage is applied to the source terminal for biasing the transistor and the mixed/downconverted output (IF) signal is obtained from the drain terminal. When the circuit is used as an RF mixer or downconverter, an RF signal is provided to the gate terminal and a local oscillator signal is provided to the back-gate terminal. The circuit includes a MOS transistor having gate, source, drain and back-gate terminals. A four terminal multiplication circuit capable of mixing up to three input signals. ![]()
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